T-Mobile has recently started some phone scam protection, although I have not seen its benefit.
Here is the main page where T-Mobile describes the new features.
Scam ID – this theoretically will mark certain phone calls as potential scammer phone calls. I have not had ANY scam phone calls sent to my phone marked by T-Mobile. This is a free service.
Scam Block – this allows you to block phone calls from known scammers. You can turn this on/off. It may block some good phone calls, but doesn’t give you the option to white-list or black-list any numbers. The problem I see is that phone scammers are continually using new technology which will hide their true identity. This is also free.
Name ID – This costs $4/month. Add Name ID and identify any caller’s name and location. I’m not sure how this is much different than the standard Caller ID which I already have. The bad guys can also hide their real name, phone numbers and location so this is of questionable value. This also allows you to block any personal number.